Enhanced biodegradation of hexachlorocyclohexane (HCH) in contaminated soils via inoculation with Sphingobium indicum B90A

Soil pollution with hexachlorocyclohexane (HCH) has caused serious environmental problems. Here we describe the targeted degradation of all HCH isomers by applying the aerobic bacterium Sphingobium indicum B90A. In particular, we examined possibilities for large-scale cultivation of strain B90A, tested immobilization, storage and inoculation procedures, and determined the survival and HCH-degradation activity of inoculated cells in soil. Optimal growth of strain B90A was achieved in glucose-containing mineral medium and up to 65% culturability could be maintained after 60 days storage at 30°C by mixing cells with sterile dry corncob powder. B90A biomass produced in water supplemented with sugarcane molasses and immobilized on corncob powder retained 15–20% culturability after 30 days storage at 30°C, whereas full culturability was maintained when cells were stored frozen at −20°C. On the contrary, cells stored on corncob degraded γ-HCH faster than those that had been stored frozen, with between 15 and 85% of γ-HCH disappearance in microcosms within 20 h at 30°C. Soil microcosm tests at 25°C confirmed complete mineralization of [¹⁴C]-γ-HCH by corncob-immobilized strain B90A. Experiments conducted in small pits and at an HCH-contaminated agricultural site resulted in between 85 and 95% HCH degradation by strain B90A applied via corncob, depending on the type of HCH isomer and even at residual HCH concentrations. Up to 20% of the inoculated B90A cells survived under field conditions after 8 days and could be traced among other soil microorganisms by a combination of natural antibiotic resistance properties, unique pigmentation and PCR amplification of the linA genes. Neither the addition of corncob nor of corncob immobilized B90A did measurably change the microbial community structure as determined by T-RFLP analysis. Overall, these results indicate that on-site aerobic bioremediation of HCH exploiting the biodegradation activity of S. indicum B90A cells stored on corncob powder is a promising technology.     

Phylogenetic Study of Methanol Oxidizers from Chilika-Lake Sediments Using Genomic and Metagenomic Approaches

Group-wise diversity of sediment methylotrophs of Chilika lake (Lat. 19°28′–19°54′N; Long. 85°06′–85°35′E) Odisha, India at various identified sites was studied. Both the culturable and unculturable (metagenome) methylotrophs were investigated in the lake sediments employing both mxaF and 16S rRNA genes as markers. ARDRA profiling, 16S rRNA gene sequencing, PAGE profiling of HaeIII, EcoRI restricted mxaF gene and the mxaF gene sequences using culture-dependent approach revealed the relatedness of α-proteobacteria and Methylobacterium, Hyphomicrobium and Ancyclobacter sp. The total viable counts of the culturable aerobic methylotrophs were relatively higher in sediments near the sea mouth (S3; Panaspada), also demonstrated relatively high salinity (0.1 M NaCl) tolerance. Metagenomic DNA from the sediments, amplified using GC clamp mxaF primers and resolved through DGGE, revealed the diversity within the unculturable methylotrophic bacterium Methylobacterium organophilum, Ancyclobacter aquaticus, Burkholderiales and Hyphomicrobium sp. Culture-independent analyses revealed that up to 90 % of the methylotrophs were unculturable. The study enhances the general understandings of the metagenomic methylotrophs from such a special ecological niche.

Electronic supplementary material

The online version of this article (doi:10.1007/s12088-015-0510-3) contains supplementary material, which is available to authorized users.     

Benzyl isothiocyanate suppresses pancreatic tumor angiogenesis and invasion by inhibiting HIF-α/VEGF/Rho-GTPases: pivotal role of STAT-3

Our previous studies have shown that benzyl isothiocyanate (BITC) suppresses pancreatic tumor growth by inhibiting STAT-3; however, the exact mechanism of tumor growth suppression was not clear. Here we evaluated the effects and mechanism of BITC on pancreatic tumor angiogenesis. Our results reveal that BITC significantly inhibits neovasularization on rat aorta and Chicken-Chorioallantoic membrane. Furthermore, BITC blocks the migration and invasion of BxPC-3 and PanC-1 pancreatic cancer cells in a dose dependant manner. Moreover, secretion of VEGF and MMP-2 in normoxic and hypoxic BxPC-3 and PanC-1 cells was significantly suppressed by BITC. Both VEGF and MMP-2 play a critical role in angiogenesis and metastasis. Our results reveal that BITC significantly suppresses the phosphorylation of VEGFR-2 (Tyr-1175), and expression of HIF-α. Rho-GTPases, which are regulated by VEGF play a crucial role in pancreatic cancer progression. BITC treatment reduced the expression of RhoC whereas up-regulated the expression of tumor suppressor RhoB. STAT-3 over-expression or IL-6 treatment significantly induced HIF-1α and VEGF expression; however, BITC substantially suppressed STAT-3 as well as STAT-3-induced HIF-1α and VEGF expression. Finally, in vivo tumor growth and matrigel-plug assay show reduced tumor growth and substantial reduction of hemoglobin content in the matrigel plugs and tumors of mice treated orally with 12 μmol BITC, indicating reduced tumor angiogenesis. Immunoblotting of BITC treated tumors show reduced expression of STAT-3 phosphorylation (Tyr-705), HIF-α, VEGFR-2, VEGF, MMP-2, CD31 and RhoC. Taken together, our results suggest that BITC suppresses pancreatic tumor growth by inhibiting tumor angiogenesis through STAT-3-dependant pathway.     

DNA-binding behavior of ruthenium(II) complexes containing both group 15 donors and 2,2':6',2''-terpyridine

Tetrafluoroborate salts of cationic ruthenium complexes [Ru(kappa(3)-tpy)(EPh(3))(2)Cl](+) (tpy=2,2':6',2'-terpyridine; E=P, 1 or As, 2) containing both the group 15 donor ligands and tpy and their representative substitution products are reported. Weak interaction {C-H...X (X=Cl, F and pi) and pi-pi interaction} studies revealed the presence of a double helical motif in complex 1, while the complex 2 assumes a single helical motif. Intercalative mode of interaction of the complexes 1 and 2 with calf thymus DNA (ctDNA) has been supported by absorption titration studies.     

Disentangling the role of soil in structuring tropical tree communities at Tarap Hill Reserve of Bangladesh

Tarap Hill Reserve, the largest upland reserve of Bangladesh, is situated along the Indo-Burma Biodiversity Hotspot. It encompasses the last remaining patches of natural vegetation in the Northeastern Tarap Mountain System and harbors 87 % of the nationally declared red-listed vascular plant species. Despite requiring high conservation priority, this is one of the least studied reserves in the tropics. In this study, we collected vegetation and soil (eight variables) data from 68 sample plots. We identified the tree communities by cluster analysis and verified them using the multi-response permutation procedure and detrended correspondence analysis. Species richness, diversity, and compositional similarity between the communities were also estimated. In total, 116 tree species representing 69 genera were recorded within the four identified tree community types. Finally, canonical correspondence analysis with associated Monte Carlo permutation tests (499 permutations) was performed to explore the patterns of variation in tree species distribution explained by the soil variables. Soil phosphorus, organic matter content, and pH were most closely correlated with tree compositional variation. Thus, conservation strategies that take into account variations in these influential soil factors may aid in the conservation of trees in the reserve.